#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int Mul(int n)
{
	if (n == 0)
		return 1;
	else
	{
		int sum = 1;
		for (int i = n; i >= 1; i--)
		{
			sum *= i;
		}
		return sum;
	}
}
int main()
{
	int n = 0;
	scanf("%d", &n);
	int sum = Mul(n);
	printf("%d", sum);
	return 0;
}